如何验证ASP.NET Core中的DI容器? [英] How do I validate the DI container in ASP.NET Core?

问题描述

在我的 Startup 类中，我使用 ConfigureServices(IServiceCollection services)方法来设置服务容器，并使用Microsoft的内置DI容器.Extensions.DependencyInjection .

In my Startup class I use the ConfigureServices(IServiceCollection services) method to set up my service container, using the built-in DI container from Microsoft.Extensions.DependencyInjection.

我想在单元测试中验证依赖关系图以检查是否可以构造所有服务，以便我可以修复单元测试期间丢失的所有服务，而不是使应用程序在运行时崩溃.在以前的项目中，我使用了Simple Injector，该容器具有 .Verify()方法.但是我找不到与ASP.NET Core类似的东西.

I want to validate the dependency graph in an unit test to check that all of the services can be constructed, so that I can fix any services missing during unit testing instead of having the app crash at runtime. In previous projects I've used Simple Injector, which has a .Verify() method for the container. But I haven't been able to find anything similar for ASP.NET Core.

是否有任何内置(或至少推荐)的方法来验证整个依赖图是否可以构建?

(我能想到的最愚蠢的方法是这样的，但是由于框架本身注入了开放的泛型，它仍然会失败):

(The dumbest way I can think of is something like this, but it will still fail because of the open generics that are injected by the framework itself):

startup.ConfigureServices(serviceCollection);
var provider = serviceCollection.BuildServiceProvider();
foreach (var serviceDescriptor in serviceCollection)
{
    provider.GetService(serviceDescriptor.ServiceType);
}

推荐答案

ASP.NET Core 3中添加了一个内置的DI容器验证，并且默认情况下仅在 Development 环境中启用了该验证.如果缺少某些内容，则容器在启动时会引发致命异常.

A built-in DI container validation was added in ASP.NET Core 3 and it is enabled only in the Development environment by default. If something is missing, the container throws a fatal exception on startup.

请记住，默认情况下不会在DI容器中创建控制器，因此，典型的Web应用程序在此检查不会获得很多收益，除非将控制器注册到DI中:

Keep in mind that controllers aren't created in the DI container by default, so a typical web app won't get much from this check until the controllers are registered in the DI:

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers()
        .AddControllersAsServices();
}

要禁用/自定义验证，请添加 IHostBuilder.UseDefaultServiceProvider 调用:

To disable/customize the validation, add a IHostBuilder.UseDefaultServiceProvider call:

public class Program
{
    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            //...
            .UseDefaultServiceProvider((context, options) =>
            {
                options.ValidateOnBuild = false;
            });

此验证功能有几个限制，请在此处阅读更多信息:

This validation feature has several limitations, read more here: https://andrewlock.net/new-in-asp-net-core-3-service-provider-validation/

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